I've been using State Fund for my worker's compensation insurance in California but they've drowned me in paperwork and the way the account works is so complicated that it's very difficult and time-consuming to even try to understand. This is for a very small and mundane company with no claims. Is there another insurance company you guys would recommend trying? State Farm?
Insurance is a heavily regulated industry. I think you will find the complications the same across the industry. Do you not use an insurance agent/broker? Their job is to help you through this. They get commission every time you renewal for this. They should be reviewing your coverage every year and helping to make sure you are adequately protected.
Just google it for your area (city/state). There are lots of them. They are mostly old school people so you will need to actually call them - not just email. Some of them may not do the type of insurance you are looking for. Workers comp is common so this shouldn't be hard. Of course, I'm in Virginia, not California, so your mileage may vary. I know California is more regulated than most states and companies leave the market regularly due to the regulatory environment.
Just an FYI -- although I'm in e-commerce now I've spend 24 years in the insurance industry. No one sane would know this much about it otherwise :-)
I'm in CA and I use Farmers. They use local face to face agents. You might check Travelers as well; not sure if they carry workmans comp but I've been impressed with the way they do business in my B&M sector. It wouldn't hurt to have an insurance broker shop your policy around, but keep their ability and willingness to help in the event of a claim in mind when you choose. This is where a local agent can be an unbeatable value.